This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Unseen Academicals
Mr. Nutt's backstory.
Nutt: But here I am. You asked why I am strong? When I lived in the dark of the forge, I used to lift weights. The tongs at first, and then the little hammer and then the biggest hammer, and then one day I could lift the anvil. That was a good day. It was a little freedom. Trevor: Why was it so important to lift the anvil? Nutt:I was chained to the anvil.
You might feel sorry for Lord Vetinari, of all people, after his description of a mother otter and her cubs feeding on a salmon and its roe:
"...Mother and children dining upon mother and children. And that's when I first learned about evil. It is built into the very nature of the universe. Every world spins in pain. If there is any kind of supreme being, I told myself, it is up to all of us to become his moral superior." The two wizards exchanged a glance. Vetinari was staring into the depths of his beer mug and they were glad that they did not know what he saw in there.
"I wrote it for you." Glenda wasn't the only person crying at that part.
The Loko business. "Children, which they killed." "Pups, which they exterminated!" Especially when we later find out that the remaining orcs have been hunted and reduced to a few dozen, merely surviving in Uberwald without any kind of organised society or hope of one.